Dynamics and Stability of Rotor-Bearing Systems

Rotor-bearing systems form the core of many high-speed machines, converting energy into rotational motion. Their dynamic behaviour is governed by the interaction between rotating shafts and supporting bearings, where factors such as mass distribution, bearing stiffness and damping properties combine to produce complex vibration patterns. As rotational speed approaches critical values, whirling motions and subsynchronous oscillations may emerge, driven by gyroscopic effects and nonlinear contact forces. Stability margins are determined by eigenvalue spectra and bifurcation thresholds, which indicate the onset of divergent amplitudes or chaotic motion. Advanced modelling techniques, ranging from finite element analysis through to reduced-order models, enable prediction and control of these phenomena. Practical applications span from aeroengine shafts, where inertial and thermal loads demand robust design, to turbochargers and electric motor spindles, where minimal vibration ensures reliability and efficiency. Recent advances have emphasised uncertainty quantification, adaptive control strategies and novel bearing technologies, all of which serve to enhance operational windows and mitigate failure risks on a global scale.

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Dynamics and Stability of Rotor-Bearing Systems publication trend

The graph below shows the total number of articles in dynamics and stability of rotor-bearing systems across all publications each year (not limited to Nature Index journals).

Technical terms

Critical speed: Rotational speed at which natural frequency and excitation coincide, leading to resonance.

Gyroscopic effect: Tendency of a spinning rotor to resist changes in orientation, influencing stability and whirl direction.

Whirl: Orbiting motion of the shaft’s centreline around the bearing axis, may be forward or backward relative to rotation.

Active magnetic bearing (AMB): Electromagnetic support system that levitates and controls a rotor without physical contact, enabling low friction and high speed.

Bifurcation: Point at which small parameter changes cause qualitative shifts in system behaviour, such as transition from periodic to chaotic motion.

References

1. A state-of-the-art review on uncertainty analysis of rotor systems. Mechanical Systems and Signal Processing (2023).
2. Nonlinear Vibrations of a Rotor‐Active Magnetic Bearing System with 16‐Pole Legs and Two Degrees of Freedom. Shock and Vibration (2020).
3. Radial Versus Cartesian Control Strategies to Stabilize the Nonlinear Whirling Motion of the Six-Pole Rotor-AMBs. IEEE Access (2020).
4. Continuation techniques for analysis of whole aeroengine dynamics with imperfect bifurcations and isolated solutions. Nonlinear Dynamics (2016).